With the continual development of modern mobile communication technology, mobile telephones have been widely used as a kind of convenient communication tool. The continual combination of mobile telephone technology, computer technology and the like makes a mobile telephone integrated with various functions, such as information storage function including address book, short message, notebook and memorandum, which play an important role in our daily life. Such information stored in a mobile telephone is usually personal privacy and it may be very important for the subscriber of the mobile telephone.
Because mobile telephones are small in volume, they are prone to be lost or stolen. When a mobile telephone of a subscriber is stolen or lost unfortunately, the subscriber may report the loss to a service provider via telephone or in a mobile business hall, so that unnecessary economic loss of call charge will be avoided. However, an implicit loss caused by the leakage of private information stored in the mobile telephone cannot be avoided. For example, short messages communicated with customers will leak out trade secret and business information, which will incur heavy economic loss of the subscriber.